Field of the Invention
The present invention relates to a technique for exhausting a gas filtered by a filter.
Description of the Background Art
Generally, an electronic circuit is manufactured by placing electronic components on a printed circuit board and securing the electronic components using soldering. As a pre-process of the soldering, a flux liquid is applied to the printed circuit board. The flux liquid is created by diluting a flux base material with a diluent such as IPA (isopropyl alcohol). The flux liquid is applied in order to, for example, remove an oxide film on the surface of the printed circuit board to be soldered.
As an applying apparatus that applies such a flux liquid, there is a known applying apparatus that injects the flux liquid from a nozzle to apply the flux liquid to a printed circuit. When the flux liquid is injected from the nozzle, the flux liquid is applied to the printed circuit board and the nebulosus flux liquid diffuses in the applying apparatus.
IPA included in the flux liquid volatilizes at room temperature and may explode if it catches fire. Accordingly, the nebulosus flux liquid (referred to below as “sprayed flux”) in the applying apparatus needs to be exhausted externally from the apparatus. If the applying apparatus exhausts the sprayed flux without performing any process on an exhaust pipe connected to the applying apparatus, the flux base material is attached to the inside of the exhaust pipe, thereby polluting the exhaust pipe. Accordingly, the applying apparatus performs filtering using a filter when exhausting the sprayed flux to the exhaust pipe, removes the flux base material, and exhausts the evaporated IPA externally from the apparatus.
There is a conventional method for filtering the sprayed flux in this way. For example, an exhaust duct with a filter is provided above the nozzle (the upper portion of the applying apparatus) to exhaust the gas having passed through the filter externally from the apparatus. In another example, a mist recovery box with a filter is provided below the nozzle (the lower portion of the applying apparatus) to filter the sprayed flux and recover the flux to the box.
However, when adopting a technique placing the exhaust duct with a filter above the nozzle, a part of the sprayed flux may remain in the applying apparatus. That is, since IPA is heavier than air and the sprayed flux including IPA is much heavier than air, a part of sprayed flux may remain below the nozzle. On the other hand, when adopting a technique placing a filter below the nozzle to filter the sprayed flux, the operator needs to stop injecting the flux liquid from the nozzle when exchanging the filter. As a result, the productivity of the applying apparatus is reduced.